1. Technical Field
The invention relates to an apparatus for the preparation and the performance of sedimentation velocity tests on previously treated organic liquids which have to be agitated in containers of test-tube type, such as the so-called E.S.R. Erytro Sedimendation Rate, and for similar uses.
2. Background Art
Such an apparatus is known from, for example, Italian Patent No. 1,233,510 and from the corresponding European Patent Publication No. 391,861 (Appl. No. 90830094.0); in the apparatus described therein, the sedimentation of the preparation takes place by means of gravity alone, and has relatively long analysis times. Such an apparatus comprises: an assembly, on a base structure, which assembly oscillates about a horizontal oscillation axis between two limit positions, a rotor, on said assembly, which rotor is capable of rotating about an axis of rotation orthogonal to said horizontal axis, a ring of seats for test tubes on said rotor, each seat being arranged and oriented symmetrically about said axis of rotation with an inclination in relation to said axis of rotation in the respective diametral plane. The apparatus also comprises means of moving said assembly into a position with the axis of rotation of the rotor roughly horizontal, to carry out an agitation stage, and into a position with the axis of rotation vertical, to carry out a reading stage. Means are provided, in a reading station, for optical reading along the test tube, when this test tube arrives in the reading station by intermittent movements of said rotor when it is arranged with the axis of rotation oriented upwards.
The aim of the invention is to shorten the time necessary for carrying out a cycle of operations (which is slowed down mainly by the stage of sedimentation by gravity) in an apparatus of the abovementioned type.
According to the invention, said rotor can be actuated by motor means withxe2x80x94in addition to relatively slow motion for agitation in the position with the axis of rotation roughly horizontal, and in addition to intermittent motion in the position with the axis of rotation vertical for consecutive positioning of the test tubes in the reading stationxe2x80x94relatively fast motion as well in order to obtain a centrifugation effect in the contents of the test tubes and therefore accelerated sedimentation, after the agitation stage and before the reading stage; moreover, in the vertical position of said axis of rotation, the test tubes are oriented, on said rotor, with their bottom facing outwards during the fast rotation for centrifugation.
According to one possible embodiment, said seats for the test tubes are fixed on the rotor and oriented with an angle of the order of 45xc2x0 in relation to the axis of rotation of the rotor, with the bottom of the test tubes further than their mouth from the axis of rotation.
According to another possible embodiment, each of said seats for the test tubes oscillates on the rotor about a tangential axis and tends to adopt, by gravity, a position parallel to the axis of rotation of the rotor when the latter is vertical and moved in order to bring the test tubes consecutively to the reading station; on the other hand, the seats and the test tubes adopt, by centrifugal effect, an inclined position during fast rotation, until they are orthogonal to said axis of rotation of the rotor.
In practice, in order to keep the test tubes in the inclined position with the bottom oriented upwards, it is possible to provide, on the oscillating assembly, a guide member along the upper trajectory of the test tubes in the position of the rotor with the axis of rotation essentially horizontal in the agitation stage. Said guide member can be moved by an actuator in order to adopt a rest position in all stages with the exception of the agitation stage.
In the centrifugation stage, the rotor can be actuated with relatively fast motion, in particular of the order of 300 revolutions per minute.
The optical reading means also comprise, on a slide capable of sliding parallel to the test tube in the reading position, reading means for bar-codes or similar, which may be present on the individual test tubes, as well as means of reading the liquid by transparency.